Such converter devices are currently used in apparatus which include a plurality of integrated circuits fed by a common ground-referenced supply voltage and which are interconnected by a printed circuit such as, for example, radio telephones. Actually, preferably symmetrical voltage signals are managed in certain integrated circuits, notably for reasons of noise reduction, which is made possible thanks to the symmetry of the structures which result from the symmetry of the signals. These symmetrical signals are preferably referenced to the supply voltage, which is often produced by a battery and thus subject to variations. The signals in transit between two integrated circuits via the printed circuit are to be of an asymmetrical type and referenced to ground common to all the circuits.
Known converter devices are mostly formed by arrangements based on operational amplifiers. Thus, a conventional converter device uses an operational amplifier arranged as a differential amplifier which generates an asymmetrical type of voltage which is representative of the symmetrical input voltage, followed by an operational amplifier commanding the conduction of a current, which is proportional to the output voltage of the differential amplifier, through a resistor connected to the ground terminal of the circuit. Such arrangements are described in the book entitled "The Art of Electronics" by Messrs. Paul Horowitz and Winfield Hill. The converter device as described above has the following major drawbacks: each operational amplifier is in itself a complex circuit comprising up to several dozen transistors. The use of such a device necessitates the use of a large silicon surface which renders it costly. In addition, when the operational amplifiers are subjected to variations of their supply voltage, they are likely to introduce a parasitic DC component in the output voltage which component may be harmful to the proper operation of the apparatus.
It is an object of the invention to largely remedy these drawbacks by proposing a converter device that has a simpler structure, calling for a reduced number of components while having a reduced sensitivity relative to variations of the supply voltage.